Supporting bushing

ABSTRACT

A supporting sleeve configured for introduction into a penetration in a component. The hole of the supporting sleeve is penetrated by a fixing pin that is insertable into a carrier so as to fix the component on a carrier. The supporting sleeve includes a closed ring-shaped cross section and a plurality of axially and inwardly extending recesses extending over the entire length of the supporting sleeve and each of the recesses is formed by inwardly bent walls and a base connecting those walls, the walls being generally radially oriented and configured such that when radial pressure is applied to the supporting sleeve upon introduction into the penetration, each recess moves closer to each other.

BACKGROUND OF THE INVENTION

The invention relates to a supporting sleeve, that is introducible intoa penetration in a component. Further the component may be fixed on thecarrier so that the hole of the supporting sleeve is penetrated by afixing pin, particularly a screw, that is insertable into the carrier.

Such a supporting sleeve is disclosed in DE-OS 195 34 034 A1. Thesupporting sleeve serves to be inserted into the penetration in acomponent and to accept a screw with which the component is screwed to acarrier. The forces exerted on the component by the head of the screwand by the carrier are absorbed by the supporting sleeve, which isfixedly anchored in the penetration in the component and whichconsequently protects any sensitive material of the component againstexcessive compressive forces exerted by the screw. In order to providethe supporting sleeve with a certain radial flexibility with which thesupporting sleeve is supported in the penetration in the component, thesupporting sleeve is provided with a longitudinal slit which, as aresult of the thereby imparted spring effect of the supporting sleeve,facilitates the insertion of the supporting sleeve into the penetrationin the component and which exerts a certain clamping effect in thepenetration.

So that the known supporting sleeve is able sufficiently to withstandthe pressure exerted by a screw, i.e. in particular the pressure of thescrew head on the respective end face of the supporting sleeve, thesupporting sleeve must have a relatively large wall thickness, which,however, has the consequence that, despite its slit, the supportingsleeve does not possess any especially great elasticity. The large wallthickness allows the supporting sleeve to be compressed only ifrelatively high radial forces are applied.

SUMMARY OF THE INVENTION

Further known from British patent specification GB 636,858 A is a wallplug which is formed by a sleeve provided with a plurality of axiallyextending recesses. The recesses consist of folds whose walls meet atthe base of the fold. This known wall plug is not formed and used as asupporting sleeve. As an inserted wall plug, its purpose is to provide asecure seat in a prepared hole in a wall and to prevent its rotationwhen a screw is being inserted and screwed in.

The object of the invention is to create a supporting sleeve whosedesign makes it possible to select the spring force of the supportingsleeve over a considerable margin, the absorption of the compressiveforces from the screw being made possible by correspondingly large endfaces of the supporting sleeve.

The object of the invention is achieved in that the supporting sleeve isformed in cross section as a closed ring and includes a plurality ofaxially extending recesses extending over the entire length of thesupporting sleeve, therefore, when radial pressure is applied to thesupporting sleeve, the walls of the recesses come closer to each otheras the bases of the recesses bend in.

The design of the supporting sleeve with a plurality of continuousrecesses extending in the longitudinal direction of the supportingsleeve results in a corresponding number of bases of said recesses, saidbases forming the region of the supporting sleeve in which the materialof the supporting sleeve can be bent. An advantageous design of thesupporting sleeve results when the supporting sleeve is provided withfour recesses, with the result that four bases are available for bendingin, said bases providing the supporting sleeve with a considerableflexibility. Of course, the supporting sleeve may also be provided withthree or even with two recesses; however, the flexibility of thesupporting sleeve naturally increases with the number of recesses, thisdeciding the elasticity of the supporting sleeve. On account of thearrangement of a plurality of recesses, there results at the end face ofthe supporting sleeve a linear cross section of the supporting sleeve,this serving in the radial direction for a corresponding width of thesupporting surface for the head of a screw or other fixing pin. The sameapplies, of course, also to the opposite end face of the supportingsleeve, which, when the component is fixed to a carrier, is in contacttherewith.

The fixing pin may primarily be a screw; however, it is also possible toemploy a nail-like pin if the leading end of the nail allows it to befixed in the carrier.

Advantageously, the recesses are uniformly distributed over the ring,this resulting in a correspondingly uniform distribution of theelasticity of the supporting sleeve over its entire circumference.

In order to captively connect the supporting sleeve to the fixing pin,the bases of the recesses are advantageously so designed that the basesof the recesses have inwardly pointing projections at one end of thesupporting sleeve. Owing to a widening of the diameter of the fixingpin, particularly by the thread of a screw, the projections form aconstriction of the hole of the supporting sleeve in relation to awidening of the diameter of the fixing pin, with the result that a screwintroduced into the supporting sleeve with a correspondingly long necksituated between the head and the thread is captively connected to thesupporting sleeve. In order to introduce the screw into the supportingsleeve, the screw is either pressed through the supporting sleeve, thesupporting sleeve yielding because of its elasticity, or the screw issimply screwed into the hole of the supporting sleeve until theprojections at the bases of the recesses come into the region of theneck of the screw.

Another type of captive connection between supporting sleeve and fixingpin consists in sliding onto the fixing pin a washer, which is supportedon one side by the constriction formed by the projections and on theother side by the widening of the fixing pin, wherein said widening may,as indicated, be in particular a thread of a screw.

So that the washer can be slid effortlessly onto a screw serving as thefixing pin, it is advantageous for the opening of the washer to be ofsuch design that it is determined by three overlapping circular areas,the centre points of said circular areas lying on a circular arc whosecentre point coincides with the axis of the supporting sleeve, the threecentre points of the circular areas being uniformly distributed on thecircular arc. This results in a circle-like opening of the washer withthree symmetrically disposed circular-arc-shaped recesses and obtuselyconverging interfaces of the circular arcs, which project as obtusecorners into the opening of the washer and thereby determine a circularring whose diameter is smaller than the diameter of the widening of thefixing pin or thread of the screw.

Advantageously, the recesses may be slightly axially elongated incomparison with the bulges (i.e. the radially external wall parts of thesupporting sleeve) which connect them, the consequence of this beingthat the carrier with the fixing pin is able, if necessary, to exertslight oscillations in relation to the component without these beingtransferred to the component, because, with this type of connection, theelongations of the recesses are fixedly connected to the carrier whereasthe component is elastically held by the bulges which support thecomponent.

In order further to increase the elasticity of the supporting sleeve,the bulges connecting the recesses may be so designed in cross sectionto form a continuous wave-like valley. In this case, there is a certainbendability of the bulges also in the region of the wave-like valley. Atany rate, this makes it possible to increase the elasticity of thecomponent in relation to the screw.

The walls of the recesses may be aligned obliquely with respect to theradial direction in such a manner that the recesses each have auniformly repeating skew position in relation to the radial direction.Said skew position may be such that, when a screw (serving as fixingpin) is tightened, there results a driving torque on the end face of thesupporting sleeve facing the head of the screw, said driving torquebeing opposed by a correspondingly obliquely positioned wall, theoblique positioning being such that the forces acting on the end faceextend more or less along the direction of the respective walls. In thisdesign, the walls are able to effectively absorb the occurringfrictional forces, this preventing the supporting sleeve from itselfrotating when a screw is tightened.

The supporting sleeve can also be advantageously so designed that therecesses determining the hole in the supporting sleeve are of such anundersize in relation to the fixing pin in the form of the screw thatthe screw cuts an internal thread when being screwed into the supportingsleeve. In this case, therefore, there is a special support between thesupporting sleeve and the screw via the thread of the screw.

The supporting sleeve may, in particular, be produced from metal.However, it is also possible for it to be injection-moulded from a hard,elastic synthetic material. During the production of the supportingsleeves, the projections for securing a screw are then either pressedinwardly or are formed during injection moulding through appropriatedesign of the mould.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the invention are shown in the drawings, inwhich:

FIGS. 1 a and b show the supporting sleeve in a perspective view and ina top view;

FIGS. 2 a and b show a modification of the supporting sleeve from FIG. 1with inwardly pointing projections, in a top view and in section;

FIG. 3 shows a perspective view of the supporting sleeve with recesses,said recesses being axially elongated in relation to the bulges whichconnect them, as well as with a wave-like valley in each bulgeconnecting two recesses;

FIG. 4 shows a modification of the supporting sleeve with walls of therecesses extending obliquely with respect to the radial direction;

FIG. 5 shows an assembly of supporting sleeve and a component fixed to acarrier by means of the supporting sleeve;

FIG. 6 shows a supporting sleeve with a washer for the captiveconnection of supporting sleeve and screw;

FIG. 7 shows a view of the washer;

FIG. 8 shows an assembly of supporting sleeve and a carrier withcomponent, the supporting sleeve having an undersize in relation to thethread of the screw.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows the supporting sleeve 1A in a perspective view, thesupporting sleeve 1 in this case comprising the four recesses 2, 3, 4and 5. Said recesses are also apparent from the top view of the end faceof the supporting sleeve 1A in FIG. 1 b. The recesses are each formed bythe two walls 6 and 7 as well as by the base 8. Extending between therecesses 2 to 5 are the bulges 9,10,11 and 12, which connect them.

This design of the supporting sleeve 1A allows the supporting sleeve 1Ato be radially compressed as a result of the flexibility of the materialof the supporting sleeve and makes it possible for the supporting sleeveto be introduced into a penetration in a component, the diameter of saidpenetration being smaller than the diameter of the supporting sleeveshown in its relaxed position in FIG. 1 a and b. When the supportingsleeve 1A is radially compressed, there results primarily a bending-inof the bases 8, the walls 6 and 7 coming closer to each other. This isaccomplished in uniform manner owing to the uniform construction of thesupporting sleeve in respect of all four recesses 2 to 5, this making itpossible to achieve a considerable elasticity of the supporting sleeve1A. With regard to the introduction of the supporting sleeve 1A and itsfunction in a component, reference is made to the below-givenexplanatory remarks in relation to FIG. 5. It can be seen from FIG. 5that the therein shown supporting sleeve 1A accepts a screw 13 in itshole 41.

In order captively to connect such a screw to the supporting sleeve 1,in FIGS. 2 a and b the bases 8 are provided with inwardly pointingprojections 15, 16, 17 and 18, which, as becomes apparent from sectionII—II from FIG. 2 a, are provided on one side of the supporting sleeve1. Said projections 16 and 18, also shown in FIG. 5, serve to preventthe screw 13 from sliding out of the supporting sleeve 1 in thedirection of its head 19. The screw 13 is prevented from doing this bythe diameter of its thread 20, the diameter of which is greater than thediameter provided by the projections 16 and 18 (as well as 15 and 17 inFIG. 2 a).

FIG. 3 shows a modification of the design of the supporting sleeve 1 inFIGS. 2 a and b, namely the supporting sleeve 21 in a perspective view,said supporting sleeve 21, like supporting sleeve 1, having fourrecesses 22, 23, 24 and 25. Said recesses with their bases and walls areaxially slightly longer than the bulges 26, 27, 28 and 29 connecting therecesses 22 to 25. The same elongation of the recesses 22 to 25 isprovided on the non-visible opposite side of the supporting sleeve 21.Owing to said elongations, a screw penetrating the supporting sleeve 21is supported with its screw head on said elongations and on a carrier(see FIG. 5), the consequence of which is that the pressure exerted bythe screw on the supporting sleeve 21 is absorbed by the aforementionedelongations, which are thus rigidly clamped. Conversely, the bulges 26,27, 28 and 29 are left with a certain flexibility, which means that acomponent accepting the supporting sleeve 21 and fixedly enclosing thesupporting sleeve 21 is able, within the range of an elasticity of theaforementioned bulges, to move slightly in relation to the fixedlyclamped elongations of the supporting sleeve 21.

The supporting sleeve 21 is further provided in the region of its bulges26 to 29 with inwardly pointing wave-like valleys 30, 31, 32 and 33,which give the supporting sleeve 21 a further elasticity, since, becauseof the wave-like valleys 30 to 33, the bulges 26 to 29 can likewise becompressed slightly.

FIG. 4 shows the top view of the end face of a supporting sleeve 34 inwhich the walls 35 and 36 of the recesses 37 extend obliquely withrespect to the radial direction, which is indicated by the arrow 38. Theoblique position of the aforementioned walls is repeated in all fourrecesses of the supporting sleeve 34. When a torque in the clockwisedirection of rotation is exerted on said supporting sleeve (by a screw,positioned on the elongations in FIG. 3, with its screw head), the wall36 is supported against the wall of the penetration in the component andin this manner provides a particular resistance against the rotation ofthe supporting sleeve 34 in the component.

FIG. 5 shows the aforementioned assembly of supporting sleeve 1 withcomponent 39 and carrier 40. The supporting sleeve 1 has been pressedinto the penetration 14 in the component 39. Inserted through the hole41 of the supporting sleeve 1 is the screw 13, which is supportedagainst the washer 42 under the screw head 19 and which, when tightened,presses with the washer 42 on the respective end face of the supportingsleeve 1. The end of the screw 13, provided with the thread 20, isscrewed into the carrier 40 and is tightened with respect to the latter,this establishing the connection between component 39 and carrier 40.The supporting sleeve 1 removes from the component 39 the compressiveforces emanating from the screw 13, with the result that a component 39made of a sensitive material is unable to be squeezed together in theregion of the washer 42.

FIG. 6 shows a variant of the connection presented in FIG. 5 in whichthe screw 43 carries the washer 45 in the region of its neck 44. Thewasher 45 is hindered with regard to its mobility on the neck 44 by thethicker part 56 of the screw 43 and also by the collar 46 formed on theneck 44. This design prevents the screw 43 from being able to beseparated from the supporting sleeve 1. The collar 46 is formed duringthe production of the screw 43 in a state in which the washer 45 isalready supported by the neck 44. Said forming of the collar 46 resultsin the tapering 47, shown in FIG. 6, of the neck 44. To enable the screw46 with the washer 45 to be introduced into the supporting sleeve 1 fromthe side of the projections 16 and 18 into the hole 41 of the supportingsleeve 1, there is provided the thicker part 56, the washer 45 coming upagainst said thicker part 56 when the screw 43 is introduced into thesupporting sleeve 1.

The washer 45 is shown in an enlarged top view in FIG. 7. The opening 48of the washer 45 is defined here by three overlapping circular areasdrawn with broken lines, the circular edges 49, 50 and 51 of which meetat the corners 52, 53 and 54 and thus form the opening 48 with threerecesses, into each of which fits the neck 44 of the screw 43 in FIG. 6.The corners 52, 53 and 54 lie on a circular arc, indicated by thedash-dotted line, the diameter of which is smaller than the diameter ofthe screw 43 in the region of the thicker part 45 or the diameter of thecollar 46. Thanks to this design of the opening 48 of the washer 45, itis possible for the screw 43 with its neck 44 to come up against each ofthe edges 49, 50 and 51, this therefore guaranteeing a considerable playbetween the screw 43 and the washer 45. The consequence of this is thatthe carrier, which defines the position of the screw 43 screwed into it,provides the component fixed to the carrier with the supporting sleeve 1with the amount of play made possible by the edges 49, 50 and 51.Consequently, this type of connection of captive screw 43 together withthe supporting sleeve 1 as well as a component and a carrier (referencecharacters 39 and 40 according to FIG. 5) guarantees the compensation ofconsiderable tolerances in the assembly of component and carrier usingthe supporting sleeve 1. FIG. 8 shows the assembly of supporting sleeve1, the carrier 40 and the component 39, in which the screw 13 has beenscrewed into the supporting sleeve 1, thereby cutting an internalthread, for which purpose the recesses determining the hole 41 in thesupporting sleeve 1 (of which the walls 6 and 7 can be seen in FIG. 8)are of a corresponding undersize in relation to the thread of the screw13. This results in a particular fixing of the screw 13 in thesupporting sleeve 1 by the internal thread cut into the supportingsleeve 1.

1. A supporting sleeve (1, 21, 34) configured for introduction into apenetration (14) in a component (39), wherein a hole (41) of saidsupporting sleeve (1, 21, 34) is penetrated by a fixing pin (13, 43)configured to be insertable into a carrier (40) so as to fix thecomponent (39) on a carrier (40), comprising: a closed ring-shaped crosssection; and a plurality of axially and inwardly extending recesses (2,3, 4, 5, 22, 23, 24, 25) extending over the entire length of thesupporting sleeve (1, 21, 34), each of the recesses (2, 3, 4, 5, 22, 23,24, 25) being formed by inwardly bent walls (6, 7, 35, 36) and a base(8) having inwardly pointing projections (15, 16, 17, 18) at one end ofthe supporting sleeve (1, 21, 34) for captive holding of the fixing pin(13) and connecting those walls, the walls (6, 7, 35, 36) beinggenerally radially oriented and configured such that radial pressure isapplied to the supporting sleeve (1, 21, 34) and each recess movescloser to each other upon introduction into the penetration (14).
 2. Thesupporting sleeve of claim 1, wherein the recesses (2, 3, 4, 5; 22, 23,24, 25) are uniformly distributed over the ring-shaped cross section. 3.The supporting sleeve of claim 1, the projections (15, 16, 17, 18) beingconfigured to form a constriction of the hole (41) of the supportingsleeve of the fixing pin (13), wherein the fixing pin (13) has adiameter greater than a diameter of the hole (41).
 4. The supportingsleeve of claim 3, wherein the constriction is configured to support awasher (45) guided by the fixing pin (43).
 5. The supporting sleeve ofclaim 4, further comprising three overlapping circular areas thatdetermine an opening (48) of the washer (45), wherein a center point ofeach of said circular areas lies on a circular arc (55), wherein thecircular arc has center points that coincide with the axis of thesupporting sleeve and wherein the three center points of the circularareas are uniformly distributed on the circular arc (55).
 6. Thesupporting sleeve of claim 1, wherein the fixing pin is a screw.
 7. Thesupporting sleeve of claim 1, wherein the supporting sleeve furthercomprises bulges between the recesses, the bulges providing the externalcontact surfaces for engaging the penetration when the supporting sleeveis introduced into the penetration.
 8. The supporting sleeve of claim 1,wherein each base (8) is configured to bend inwardly in response to theapplication of radial pressure upon introduction into the penetration(14).